Vises such as contemplated herein are commonly used for building and repair projects of all kinds. A typical vise is one having a pair of jaws with one of the jaws rigidly fixed to a workbench. A second jaw is movable by a transfer mechanism toward and away from the first jaw. The jaws are initially opened, a work piece is placed between the jaws in the desired position, and then the jaws are closed to hold the work piece for whatever job is to be performed on it.
It is important that the jaws of the vise are capable of applying sufficient clamping or holding pressure so that the work piece will not be easily dislodged, even when the job being performed involves sawing, hammering or the like. To ensure that adequate clamping pressure is available, the transfer mechanism is generally provided by a screw arrangement. A female screw in the form of a threaded block is secured to the workbench at a position spaced from the stationary jaw and a male screw in the form of a threaded shaft is threadably engaged with the block. One end of the shaft carries the second jaw and the other a handle which enables the operator to screw the shaft through the block and thus screw the second jaw toward and away from the first jaw.
The vise is generally adapted to hold work pieces having a wide assortment of dimensions. Thus in one situation a work piece may be held with the jaws spaced less than an inch apart. In another situation the jaws may be ten, twenty or more inches apart. The typical screw thread configuration provides for advancement of the male screw shaft in the order of 1/8 of an inch or less for each revolution of the shaft. Moving the second jaw several inches toward or away from the first jaw therefore requires dozens of revolutions. This is time consuming and wasteful of the operator's energy.